Underfloor heating insulation cracking

[emphasis303]

Hello everyone

I am tilling my floor with 12mm travertine and underfloor heating cable.

I installed ply ontop of my floorboards and then used a flexible floor adhesive and fitted 6mm insulation ontop of the adhesive with a notched trowel.

The only problem is now when I walk overe the insulation I can hear it cracking, it seems the insulation on the low points or where there is not adhesive between the notches the board has nothing to support it.

What should I do?

Rip it all up meaning ill have to remove all of the adhesive which is rock hard now? Or tile ontop of this?

Thank you very much.

 

[PrenticeBoyofDerry]

Tiling on top of it, is not going to resolve your problem, it is likely your tiles will crack.

 

[Richard C]

For whatever reason either the insulation board isn’t fully supported or the floor structure is insufficiently rigid. Unfortunately I don’t think you have any choice but to rip it up & start again or your tiles will almost certainly fail. Some questions for you;

What is the original flooring made of?
What thickness ply did you use to overboard & how did you lay it?
What size/pitch/span are your joists?
What make is the insulation board?
What size notched trowel did you use?
What make/type of adhesive did you use?

 

[emphasis303]

Original flooring is timber floorboards, spacing between joists is 300mm.

Then 12mm ply screwed on top.

XPS insulation boards.

3mm notched trowel

Mapei Pro flexible.

The floor is solid, no flexing nothing.

The problem is when I laid the insulation I guess it didnt compress enough in some places.

Ive gone over it all with a wooden board and with my feet to try and squash all of them down which has caused creaking and cracking so it no longer cracks when I walk.

If I had just screwed the board down or fully compressed it I dont think this would have been an issue.

Thank you

 

[Richard C]

spacing between joists is 300mm.

Do you know what the joist size & span are?

Then 12mm ply screwed on top.

Best to screw into the joists not just into the top of the floorboards; watch for pipes & cables.

XPS insulation boards.

Which one; are you sure they are suitable for under tile heating over a suspended floor? Not familiar with them but I've had a quick look & the ones I looked at were only suitable for use under timber floors, not under tiled floors!

3mm notched trowel

Who advise a 3mm notch trowel; too small & won’t give you 100% coverage which is essential on suspended timber floors.

The problem is when I laid the insulation I guess it didnt compress enough in some places. I’ve gone over it all with a wooden board and with my feet to try and squash all of them down which has caused creaking and cracking so it no longer cracks when I walk.

What do you mean by compress the insulation? Again which board have you used? For tiled floors the backer boards must be rigid & are usually cement based!